Chapter 20

Go right and jump the gap, then notice two sets of beams, one vertical and one horizontal. These beams trigger machine guns to fire at you if you touch them, so dig deep and jump right so that you touch the vertical beam in the air, then quickly jump back left to the platform as both guns fire.

This gets the top gun moving so go left and wait on top of the left gun. Trigger the top gun here and run out of the way so it shoots the bottom gun. Repeat this once more and the bottom gun is trashed, then jump right past the other gun and keep right and walk down the hill to a pair of Boxes and the next chapter.